export default {
  namespaced: true,
  
  state: () => ({
    cart: JSON.parse(uni.getStorageSync('cart') || '[]')
  }),
  mutations: {
    addToCart(state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      // 如果没有 就会返回undefined  
      // undefined取反之后就是true
      // 也就是当state里面的cart没有该商品的时候
      if (!findResult) {
        state.cart.push(goods)
      }else {
        // 如果找到了 findResult就是那个id相等的商品
        findResult.goods_count++
      }
      
      this.commit('m_cart/saveToStorage')
    },
    saveToStorage(state) {
      uni.setStorageSync('cart', JSON.stringify(state.cart))
    },
    // 更新购物车中商品的勾选状态
    updateGoodsState(state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      
      if(findResult) {
        findResult.goods_state = goods.goods_state
        this.commit('m_cart/saveToStorage')
      }
    },
    // 更新商品的数量 
    updateGoodsCount(state, goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      if(findResult) {
        findResult.goods_count = goods.goods_count
        
        this.commit('m_cart/saveToStorage')
      }
    },
    // 根据id删除对应的商品
    removeGoodsById(state, goods_id) {
      state.cart = state.cart.filter(x => x.goods_id !== goods_id)
      this.commit('m_cart/saveToStorage')
    },
    // 更新购物车中所有商品的状态(点击了全选按钮之后)
    updateAllGoodsState(state, newState) {
      state.cart.forEach(x => x.goods_state = newState)
      
      this.commit('m_cart/saveToStorage')
    }
  },
  getters: {
    // 购物车中所有商品的总数量
    total(state) {
      // let c = 0
      // state.cart.forEach(x => c += x.goods_count)
      // return c
      
      return state.cart.reduce((total, item) => total += item.goods_count, 0)
    },
    // 购物车中已勾选商品的总数量
    checkedCount(state) {
      return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_count , 0)
    },
    // 已勾选商品的总价格
    checkedGoodsAmount(state) {
      return state.cart.filter(x => x.goods_state).reduce((total, item) => total += item.goods_count * item.goods_price, 0).toFixed(2)
    }
  }
}